I've had my ebike since sept/16 and the 400mm Suntour NCX SP-12 was the first thing I purchased. I used this without any issues until I decided to try the Kinekt Bodyfloat by Cirrus cycles 350mm seatpost with orange springs in Feb/2017 (B-day gift to myself). The 420mm bodyfloat wasn't available at the time and the +$320 carbon fiber Bodyfloat 420mm was a little too much. The 350mm Bodyfloat did a better job at reducing the smaller bumps in the road like tree roots, uneven sidewalk cracks, and buckled asphalt compared to my Suntour NCX SP-12. I think it is because you can adjust the Bodyfloat to sag a bit into a sweet spot and the (e)bike moves under you with small vibrations. On the Suntour NCX SP-12, it felt like I was sitting on top of a spring and I still felt small vibrations being transmitted instead of floating over them. Both did equally well over larger bumps like transitioning from a road to the sidewalk at 10-15 mph or riding over neighborhood speed bumps at speed.
I continued work commuted/trail ride with the 350mm Bodyfloat for about 3-4 months at 50-75 miles per week until my right knee started to ache a little bit. It was because the Bodyfloat was a touch too short for me and had to switch back to the 400mm Suntour seatpost (I just put the 350mm Bodyfloat on my old XL Transeo GT pedal commuter bike). You can adjust the Bodyfloat with as much or as little float you like to have. Because I set it up with the float feature, the seat post suspension would sag about and inch when sitting and turning my 350mm post into maybe a 320mm (the reason for biking was because my knees were hurting from walking and jogging).
It wasn't until the fall/2017 Kinekt Bodyfloat came out with a 420mm v2.0 version and discount code for almost $40 off. I switched back and been riding with the 420mm Bodyfloat since. I have around 4400 miles on my two ebikes with about 1/2 with Suntour and rest of the time split between the 350mm and 420mm Bodyfloats. Zero maintenance issues with both and they perform as advertise work commuting and trail riding.
If someone is going to test ride the new suspension seatpost, I would try and do a comparison test with the other big three like Bodyfloat, Suntour, and Thudbuster on the same types of (e)bikes. My ebike also has front suspension, 26X4" fat tires set to 20 PSI, and Sunlite Cloud-9 seat to reduce bumps compared to (e)bikes that don't have the same set-up.
